Multi-lumen catheters are used for the purpose of creating two or more separate fluid pathways, such as in hemodialysis applications. A primary goal of hemodialysis access is to provide a reliable and effective means of dialysis, which means that a sufficient volume of blood over a period of time must be removed from and returned to the patient. Because the contaminated and cleansed blood must be kept separate for an effective dialysis procedure, a dual lumen catheter is generally used. Typically, a dual lumen catheter for hemodialysis is configured so that there is a shorter lumen that aspirates blood from a blood vessel of a patient to a dialysis machine where it is processed for the removal of toxins, and a longer lumen that infuses the purified blood to the patient. The shorter lumen utilized for aspiration is generally referred to as the “arterial lumen,” while the longer lumen utilized for infusion is generally referred to as the “venous lumen.” The reason for the different lengths is to minimize co-mingling of aspirated and infused blood.
The primary problems occurring in dual lumen dialysis catheters include thrombosis and fibrin sheath formation, which can act to occlude distal tips of the dialysis catheter lumens, resulting in loss of catheter function when such an occlusion prevents blood flow. This typically occurs initially in the arterial lumen used for aspiration of blood from a patient. A secondary problem relates to the arterial lumen “sucking” against the vessel wall, in which the arterial lumen openings become fully occluded by the patient's vasculature. To specifically address these problems, a unique type of dialysis access catheter has been designed that utilizes independent “free floating” distal tip sections that separate at a distal end of the catheter in order to reduce the likelihood of potential occlusion and “sucking” during dialysis treatment, hereinafter referred to as a “split-tip catheter.” Examples of patents and patent applications describing split-tip catheters include U.S. Pat. No. 6,001,079 to Pourchez, U.S. Pat. No. 6,758,836 to Zawacki, U.S. Pat. No. 7,393,339 to Zawacki, and co-pending U.S. patent application Ser. No. 10/842,586, filed May 10, 2004, all of which are incorporated by reference herein.
While the split-tip catheter design has led to improved functioning of dialysis catheters, it has been difficult to manufacture a split-tip catheter having reinforcement along a length thereof due to the change in configuration at the distal end. As one of skill in the art readily appreciates, a reinforcing region is desirable in an implanted catheter to prevent kinking of the catheter and/or a reduction in the catheter lumen(s) due to external pressures. Accordingly, provided herein are improvements to the design and manufacture of a multi-lumen catheter, and in particular a split-tip catheter, with respect to reinforcement along a length thereof.